Preliminary findings of research into tail docking by Alliance Group have found that leaving a lamb's tail longer or intact has no long-term beneficial or detrimental effect on its growth rate.
The southern-based company has just completed the first year of a three-year study.
Tail docking is common practice among New Zealand farmers. It is thought to help reduce dag formation and the risk of fly strike, a major cost to the sheep industry. However, to date there has been little objective information or research on the benefits, or otherwise, of the practice.
The research, involving a nationwide farmer survey and field trials in Southland, Canterbury and Manawatu, was supported by the Ministry for Primary Industries' sustainable farming fund, UK supermarket Sainsbury's and Beef and Lamb New Zealand.
Early findings suggested that tail length has no effect on time spent on-farm or on productive traits such as carcass weight. However, longer and intact tails increased the level of dag accumulation, and consequently took more time to crutch.
The link between tail length, dags and fly strike remained inconclusive, so further data would be collected in the remaining two years of the study.
The study suggested that leaving the tail longer or intact could have a positive effect on total meat yield. However, that was inconclusive as it was not consistent across breed and sex of the lamb, and further research is to be undertaken.
Alliance Group's livestock general manager Murray Behrent believed the first year of the trial had been successful.
''There is currently a lack of scientific information addressing the productive, economic and welfare aspects of docking lamb tails. This situation leaves New Zealand farmers vulnerable to any concerns from international markets in regards to the actual length of tails docked.
''It is therefore important that any welfare issues that concern consumers and have the potential to become barriers in our international markets are addressed so that we can respond on a scientific basis with available trial data,'' Mr Behrent said.
The study was important to support the image of New Zealand product in key markets, he said.
Evaluation of the economic benefit and/or the cost to the farmer of leaving the tail longer, or intact, would be part of the remaining two years of the study.
Alliance Group and its research partner, Dunedin-based AbacusBio have been working with sheep farmers and tailing and shearing contractors as part of the study.
The company will conduct an online survey of sheep farmers in August in an effort to understand the prevalence of the different docking practices and gain an insight into docking decisions made by farmers.
As part of the research, a best practice booklet on tail docking will also be developed and distributed to suppliers in 2015.